經常使用javascript類型判斷

//判斷是否是數組
console.log(Object.prototype.toString.apply([])==='[object Array]')
//判斷是否是函數
console.log(Object.prototype.toString.apply(function(){})==='[object Function]')
//判斷是否是null
console.log(Object.prototype.toString.apply(null)==='[object Null]')
//判斷是否是undefined
console.log(Object.prototype.toString.apply(undefined)==='[object Undefined]');
//判斷是否是字符串
console.log(Object.prototype.toString.apply('str')==='[object String]')